The Japan Meteorological Agency is planning to start delivering the Earthquake Early Warning (emergency information) to the public (television, radio, administrative radio communication for disaster prevention, announcement in an amusement facility, and the like) on Oct. 1, 2007. The Earthquake Early Warning (emergency information) is also expected to be delivered to mobile terminals.
In addition, there is a request from local governments to deliver emergency information to a majority of users in the event of emergency such as a disaster. Accordingly, there is a need to instantly deliver emergency information of a terror, a warning, a large-scale accident, or the like to a majority of users.
However, a current mobile communication system (a mail delivery system and the like) is not capable of instantly delivering emergency information to a majority of mobile terminals in view of radio communication resources. Accordingly, a broadcasting system is needed to meet the requirements for such instant, large-scale delivery.
The CBS (Cell Broadcast Service) and the MBMS (Multimedia Broadcast Multicast Service) are known as schemes standardized in the 3GPP to build the broadcast system.
However, it takes approximately 10 seconds for such an existing broadcast system to deliver emergency information to a majority of mobile terminals.
This is because a network has to activate a broadcast communication function (for example, a CBS receiving function) of each mobile terminal, before delivering emergency information as a broadcast communication message. Keeping the broadcast communication function of the mobile terminal active all the time significantly influences the running time of the battery.
It is strongly demanded socially to shorten as much as possible the time needed to deliver emergency information, such as Earthquake Early Warning, that may affect human lives, because the shortening of the time may lead to saving the human lives. The time needed to deliver emergency information should be reduced to several seconds
There is also a demand for emergency information to be delivered to a user roaming in a country other than the user's own country.
Each mobile terminal is configured to receive only the broadcast communication message having a message identifier included in a “reception ID list (a list of message identifiers each identifying a broadcast communication message to be received)” that the mobile terminal itself holds. For this reason, in order for the mobile terminal to receive a broadcast communication message notifying of emergency information in a country other than the user s own country, there is a need to define an internationally-common message identifier (emergency information message identifier) identifying a broadcast communication message notifying of emergency information.
However, in Japan and other countries, each telecommunication carrier has already defined its own emergency information message identifier, and a mobile terminal in a memory of which an emergency information message identifier defined by its own telecommunication carrier is written is already in widespread use. This results in the coexistence of a mobile terminal having a “reception ID list” in which an emergency communication message identifier common across the world is set and a mobile terminal having a “reception ID list” in which an emergency information message identifier unique to its own telecommunication carrier is set.
In such a circumstance, the network for delivering emergency information as a broadcast communication message needs to transmit both of a broadcast communication message including an emergency information message identifier that is common across the world and a broadcast communication message including an emergency information message identifier uniquely given by a telecommunication carrier. This causes the problem that reception delay occurs among the mobile terminals that receive the broadcast communication messages respectively including different emergency information message identifiers.
To solve this problem, there should be a migration method taking account of a circumstance where there coexist a mobile terminal using an emergency information message identifier unique to its own carrier and a mobile terminal using an emergency information message identifier common across the world, the emergency information message identifiers being used to determine whether or not to receive an emergency information message. Specifically, the migration method is to conduct gradual unification to an emergency information message identifier common across the world, while delivering, as a broadcast communication message, emergency information also to a mobile terminal having an emergency information message identifier unique to its own telecommunication carrier, without reception delay among mobile terminals respectively using different emergency information message identifiers.